the African continent from Kenya on the East coast to Angola on the West coast. It has been found in Malawi, Zaire, Zambia and Zimbabwe. The genus Vanilla has a very unusual distribution compared to other orchid genera. They have a pantropical distribution, being found throughout tropical Central and South America, Africa (including Madagascar) and Indonesia. Initially this distribution was believed to be of Gondwanan origin, with species dispersing before the continents separated. However, recent molecular work has suggested the group originated in South America around 34 million years ago, which is after the breaking up of the continents. Therefore their current distribution was probably achieved through various transoceanic dispersal events. Taxonomy and systematics V. polylepis was described in 1951 by botanist Victor Samuel Summerhayes, who has described other species in the genus. The genus has been described as taxonomically difficult for various reasons. Firstly, it was named and described before Linnaeus's binomial naming system, meaning that many of the traditional names and species groups were difficult to incorporate into the standardised binomial system. Biologically it has also been difficult for taxonomists, as the group lacks clear, shared morphological features (synapomorphies). Also, their hemiepiphytic lifestyle means that their appearance can change significantly throughout their lifetime. Many of the original species descriptions used only young plants, and as a result the morphological identifiers can no longer be applied to all specimens. Major morphological revisions have therefore been made in recent years. The orchid family has five subfamilies. Morphology-based systems initially classified Vanilla within the subfamily Epidendroideae, due to its anther formation and method of pollen dispersal. However, more recent work has placed it within in its own subfamily Vanilloideae, possibly the most ancient orchid lineage (apart from Apostasioideae). For a long time the genus Vanilla was divided in two sections, Foliosae and Aphyllae, based on the respective presence/absence of leaves. The most recent morphological classification however has shown that these two sections are not true evolutionary groups. Instead it divides the genus into two subgenera: Vanilla and Xanata, with the subgenus Xanata being subdivided into two further sections Xanata and Tethya. V. polylepis was placed in the section Tethya along with other African species, such as V. imperialis and V. grandifolia. Molecular work has supported the positioning of Vanilla within the subfamily Vanilloideae and has confirmed the genus and the subfamily as true evolutionary groups (monophyletic). Despite the morphological homogeneity of